1. Field of the Invention
This invention relates to collapsible support structures. More specifically, the present invention relates to support structures that are collapsible to reduce their width. A plurality of such support structures are combined with similar or other types of support structures to form folding devices, such as chairs, shopping carts, and trailer covers.
2. Description of the Prior Art
Numerous types of collapsible structures are known to the prior art. For instance, U.S. Pat. No. 430,703 describes a portable chair having members interconnected by hinges. U. S. Pat. No. 2,766,813 describes a collapsible chair having vertical members interconnected by cross-diagonal members. U.S. Pat. Nos. 3,736,021 and 3,968,991 describe collapsible or folding wheelchairs.
Representative problems encountered with use of previously known foldable support structures include the need to use an excessive number of component parts, a limitation on the amount of size reduction obtainable with the collapsible structures, difficulty in moving the structures between collapsed and erect or supporting positions, and a lack of rigidity when the structures are in supporting positions.